Sergio Costa

<h4>A very simple but very effective SEO plugin</h4>
<h4>No programming skills needed!</h4>
The plugin injects:
<ul>
<li>Variables
<ul>
<li>Title</li>
<li>Description</li>
<li>URL</li>
<li>Tags</li>
</ul>
</li>
<li>Meta tags
<ul>
<li>Author</li>
<li>Keywords</li>
<li>Description</li>
<li>Copyright</li>
<li>Robots (for any hierarchical file)</li>
</ul>
</li>
<li>og: tags
<ul>
<li>Title</li>
<li>Type</li>
<li>URL</li>
<li>Image</li>
<li>Site Name</li>
<li>Description</li>
</ul>
</li>
<li>dc. tags
<ul>
<li>Source</li>
<li>Relation</li>
<li>Title</li>
<li>Keywords</li>
<li>Subject</li>
<li>Description</li>
</ul>
</li>
<li>geo location tags
<ul>
<li>Placename</li>
<li>Position</li>
<li>ICBM</li>
</ul>
</li>
<li>Google Analytics code</li>
</ul>
New features are coming soon!!!

SC Simple SEO

I'm a Ninja

This interlinking plugin for WordPress will let you easily and meaningfully link to your old articles, pages or other sites to improve their rankings in search engines and generate more clicks.
The Internal Link Building plugin lets you assign keywords to given destination URLs. This way your website will link within itself like it’s done in Wikipedia – every time a keyword occurs, it links to the page you specified in the plugin dashboard.
You can: 
* set the words to be case sensitive (to only interlink your brand name for example), 
* make links nofollow (makes sense when you link to affiliate products), 
* upload keywords in bulk, etc
Note: Please do use the plugin in moderation to avoid over-optimization. Meaningful and user-friendly inter-linking goes a long way!
This plugin is supported by <a href="http://www.internetmarketingninjas.com/" rel="nofollow ugc">Internet Marketing Ninjas</a>.
<h3>Arbitrary section</h3>
The settings page is under the Posts menu -> Keywords in 2.7+. It’s under Manage -> Keywords, in older versions of WP (up to 2.5 or 2.6) .
<ol>
<li>
This plugin allows you to mass-upload keywords. So you just need to prepare a CSV file in Excel and then copy-paste it into the mass-upload box in your admin panel and then click upload! This is great for larger sites targeting multiple keywords that want to speed things up.
</li>
<li>
It’s up to you whether you make cAsE ReLeVaNT to your links. Check the “Exact Match” checkbox for it to only match when the case is the same as you typed the word into the admin panel. Leave it unchecked to have all cases link to your selected page.
</li>
<li>
Post-level overrides of globally-assigned keywords.
</li>
<li>
Link to sources or affiliate links whom you reference a lot.
</li>
<li>
Build internal links automatically to pages you regularly reference.
</li>
<li>
Make a link nofollow. For example, if you link to particular Wikipedia pages a lot then set the nofollow to be automatic.
</li>
<li>
Link multiple keywords to a single URL. Target all a page’s keywords at once! Just put a space, a pipe (eg |) and a space between the multiple keywords. E.g. affiliate | affiliate marketing. More efficiency! More time savings!
</li>
<li>
Pick the number of times a keyword will link to a particular URL. If you only want the words social media to link to your social media category once, you can do that. Notice that social gets linked next, since I also have that keyword assigned to link to the same page.
</li>
</ol>

Internal Link Building

line 706 of plugin is considered unsupported operator, didn't check the file itself, but going to leave this here for debug purpose.

not working since 4.7.3

This plugin will let you easily link to your old articles, pages or other sites to improve their rankings in search engines and generate more clicks.

SC Simple SEO vs Internal Link Building